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Trait anoma_apps::std::prelude::rust_2018::Clone

1.0.0 · source · [−]
pub trait Clone {
    fn clone(&self) -> Self;

    fn clone_from(&mut self, source: &Self) { ... }
}
Expand description

A common trait for the ability to explicitly duplicate an object.

Differs from Copy in that Copy is implicit and an inexpensive bit-wise copy, while Clone is always explicit and may or may not be expensive. In order to enforce these characteristics, Rust does not allow you to reimplement Copy, but you may reimplement Clone and run arbitrary code.

Since Clone is more general than Copy, you can automatically make anything Copy be Clone as well.

Derivable

This trait can be used with #[derive] if all fields are Clone. The derived implementation of Clone calls clone on each field.

For a generic struct, #[derive] implements Clone conditionally by adding bound Clone on generic parameters.

// `derive` implements Clone for Reading<T> when T is Clone.
#[derive(Clone)]
struct Reading<T> {
    frequency: T,
}

How can I implement Clone?

Types that are Copy should have a trivial implementation of Clone. More formally: if T: Copy, x: T, and y: &T, then let x = y.clone(); is equivalent to let x = *y;. Manual implementations should be careful to uphold this invariant; however, unsafe code must not rely on it to ensure memory safety.

An example is a generic struct holding a function pointer. In this case, the implementation of Clone cannot be derived, but can be implemented as:

struct Generate<T>(fn() -> T);

impl<T> Copy for Generate<T> {}

impl<T> Clone for Generate<T> {
    fn clone(&self) -> Self {
        *self
    }
}

Additional implementors

In addition to the implementors listed below, the following types also implement Clone:

  • Function item types (i.e., the distinct types defined for each function)
  • Function pointer types (e.g., fn() -> i32)
  • Tuple types, if each component also implements Clone (e.g., (), (i32, bool))
  • Closure types, if they capture no value from the environment or if all such captured values implement Clone themselves. Note that variables captured by shared reference always implement Clone (even if the referent doesn’t), while variables captured by mutable reference never implement Clone.

Required methods

Returns a copy of the value.

Examples
let hello = "Hello"; // &str implements Clone

assert_eq!("Hello", hello.clone());

Provided methods

Performs copy-assignment from source.

a.clone_from(&b) is equivalent to a = b.clone() in functionality, but can be overridden to reuse the resources of a to avoid unnecessary allocations.

Implementations on Foreign Types

Shared references can be cloned, but mutable references cannot!

Shared references can be cloned, but mutable references cannot!

source

impl Clone for _Unwind_Action

source

impl Clone for _Unwind_Reason_Code

impl Clone for __c_anonymous_ptrace_syscall_info_entry

impl Clone for __c_anonymous_sockaddr_can_tp

impl Clone for __c_anonymous_sockaddr_can_j1939

impl Clone for input_keymap_entry

impl Clone for _libc_xmmreg

impl Clone for __exit_status

impl Clone for __timeval

impl Clone for __c_anonymous_ptrace_syscall_info_exit

impl Clone for _libc_fpxreg

impl Clone for _libc_fpstate

impl Clone for __c_anonymous_sockaddr_can_can_addr

impl Clone for __c_anonymous_ptrace_syscall_info_data

impl Clone for __c_anonymous_ptrace_syscall_info_seccomp

Clones this PollSender.

The resulting PollSender will have an initial state identical to calling PollSender::new.

Clones the generator by deterministically deriving a new generator based on the initial seed.

Example
// Seed two generators equally, and clone both of them.
let base1 = fastrand::Rng::new();
base1.seed(0x4d595df4d0f33173);
base1.bool(); // Use the generator once.

let base2 = fastrand::Rng::new();
base2.seed(0x4d595df4d0f33173);
base2.bool(); // Use the generator once.

let rng1 = base1.clone();
let rng2 = base2.clone();

assert_eq!(rng1.u64(..), rng2.u64(..), "the cloned generators are identical");

impl Clone for enum_

impl Clone for post_return

impl Clone for bool_

Returns a copy of the atomic value.

Note that a Relaxed load is used here. If you need synchronization, use it with other atomics or fences.

Creates another reference to the same garbage collector.

Cloning an ANSIGenericString will clone its underlying string.

Examples

use ansi_term::ANSIString;

let plain_string = ANSIString::from("a plain string");
let clone_string = plain_string.clone();
assert_eq!(clone_string, plain_string);

Clones this PollSender. The resulting clone will not have any in-progress send operations, even if the current PollSender does.

impl Clone for __fsid_t

impl Clone for __va_list_tag

Implementors